It will be interesting to see if the C's go for Griffin or not. As others have said, he's lost a significant amount of his explosiveness, but that part of his game was mostly for show. He never actually built his offensive game on explosiveness, and has played quite well after coming back from his injuries this year. He'd make us quite a bit better.
Other than Griffin, and possibly Ibaka, there isn't anyone on the free agent market that's any better than what we already have. We either make a major trade, uncover some hidden gem somewhere, or make do with Yabusele and Zizic. I could see them both being important rotation players. Both guys are very strong, aggressive and long armed, which we desperately need.